1. Field of the Invention
This invention relates to a plastic squeeze vessel. More particularly, the invention relates to a plastic squeeze vessel composed of a plastic laminate having deformability and shape restoring property suitable for squeezing and high interlaminar peel strength.
Squeeze vessels composed of various flexible laminates have heretofore been proposed as squeeze tube vessels for highly viscous materials such as dental creams, cosmetics and foods and squeeze bottles for viscous foods such as ketchup, mayonnaise, jam and chocolate.
In general, these flexible laminates comprise an intermediate oxygen barrier layer composed of a saponified ethylene-vinyl acetate copolymer or nylon and layers of an olefin resin such as polyethylene laminated on both sides of the intermediate layer. In the process for forming tubes from these laminates, constituent layer sheets are lapped and bonded to form a cylinder and a screwed squeeze opening and a conical shoulder portion contiguous and connected to the screwed opening formed by injection molding of a resin are bonded to one end of the cylinder while the other end of the cylinder is closed by fusion bonding or the like.
In the formation of squeeze bottles, a multi-layer parison having the above-mentioned laminate structure is hollow-molded in a split mold to obtain a bottle.
These known squeeze vessels, however, are still insufficient in the combination of deformability, memory property of shape restoring property and interlaminar peel strength which are necessary for attaining a good squeezability.
For example, a plastic squeeze vessel is different from a squeeze vessel composed of an aluminum foil or a laminate of an aluminum foil and a plastic layer in the point that when a certain pressing deformation is given and it is then released, the original shape is restored because of too high a restoring property. Accordingly, when the vessel is sealed by a lid after the use and is stored again, a large quantity of air is sucked in the vessel and the content is deteriorated by oxygen in the vessel. Moreover, because of the excessively high restoring property, when the amount of the content left in the vessel becomes small, the content cannot be squeezed out unless the vessel wall is considerably pressed and deformed. Still further, since air is included in the vessel, at the time of pressing deformation, the content in an amount much larger than the amount to be used for one time is squeezed out or scattered singly or together with air, resulting in wasteful consumption of the content or contamination of a garment, a table or a table cloth.
In case of a squeeze vessel required to have a high transparency, by the pressing force applied to squeeze out the content or the repeated deformation given to the vessel, peeling is readily caused between the oxygen barrier layer and the olefin resin layer and as a result, the transparency is drastically degraded (that is, a so-called blanching phenomenon takes place), or the resistance to premeation of oxygen or water vapor is drastically lowered.